How much could a disease spread before discovered?

Question

In my world there is a disease called the "Ravager Plague," and it infects the "Patient Zero" in a nation's capital, a city of 512 Million people. The disease has the following symptoms:

STAGE 1(39 Hours to 2 days) - Sneezes/coughs; - Increased tiredness; - Redness in the eyes; - Paleness; - decreased physical activities.

STAGE 2(3 days to 6 1/2 days) -Numbness in the limbs; -Inability or loss of speaking

STAGE 3(7 days to 12 days) - Audio/Visual Hallucinations; - Small bumps on limbs; - Paranoia; - minor Insanity

The time for the disease to manifest is roughly 2 1/2 Days(39 Hours), with the tiredness and redness appearing first, at 40 Hours, the others showing up within 2 days.

The spores are spread through the sneezes, and the tiredness and physical activities let the spores breed and manifest in the host's body, eventually leading to stage 2.

How long would it take, if at all, until the disease was found? How would it spread, and how long until the entire capital was infected(if at all)?

The city is a 21st Century city.

Answer 1

I really think that it would depend on the state of the healhcare system of the city, and the situation of patient zero.

21st century cities have very different situation regarding healthcare : it can be public, easy to access or expensive and reserved for the wealthy, or even assumed by foreign NGOs (only in very poor countries though - I'm thinking about Madagascar and the spread of the pulmonic plague). Also, is the disease a rapid killer ? Sudden deaths attract more attention...

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" Deaths occur within 5 days to a week... The Healthcare system is also one of the best in the region, with it being completely free, with the utmost care for ALL citizens."

Then it is almost impossible for the disease to stay undiscovered for more than a week and a half I'd say... Because people would go to the hospital immediately, as soon as stage 2 at least.

There are other things to take into account : discovering is not treating, but it really helps stop the spreading by putting up quarantines for example. Also, a major parameter is the contagion rate : a very high contagion rate (20 people infected by a patient every day for example) would be disastrous for the city, but it is also not very realistic : people can be resistant to diseases. Even one of the worst epidemic in history, the Great Plague, only killed 1/3 of the European population in a relatively long time (5 years). Of course population was not as concentrated but still...

I think you can find content about the field of epidemiology that can teach you the way real crisis have been dealt with (ebola, aids, recent episodes of plague) and give you inspiration !

Answer 2

Short answer:

3 weeks, at which point the whole city would be infected.

(Edited: half the city would be infected or dead and investigations would start about a week and a few days from the initial Patient Zero infection.)

Long answer:

Suppose Patient Zero acquires these symptoms and they show up in 48 hours; they then begin to spread this around. If everyone interacts with, say, 30 people a day and sneezes while talking to 25 of them, perhaps 15 of them will get infected from the spores depending on how infectious it is. Since Patient Zero isn’t taking any precautions since this is a new disease, it is possible that when they sneeze and throw out the tissue the spores remain there and infect whoever goes near that garbage bin for the rest of the day (say, 5).

In any case, say 20 people total are infected by Patient Zero on this third day. These twenty people, in turn, then each infect 20 people two days later with Patient Zero infecting 20 more people each day.

This would spread rapidly through the population depending on how large the city is, and even by the second or third week the whole capital would be infected - this because perhaps Patient Zero infects someone who meets many many people a day or someone who isn’t hygienic and sneezes on their hands and smears it all over public transport… the opportunities for infection are endless. Perhaps by this point - the second week when about ⅔ the population is infected - an investigation would begin, but it probably wouldn’t be fully found out by week 3 when everyone’s infected. Then the whole city would go into quarantine and if anyone had travelled in those 3 weeks they could spread it across the world, and panic would ensue.

This could be even faster if it can infect rats and other non-animals; they could, in turn, spread it from the city.

It could be slower if someone gets worried and goes to healthcare services; however, the symptoms are benign enough no one would pay attention.

Without further details about the nature of the spores and how long they can last on inorganic material and how big the city is, it would be hard to say.

EDITED to include new information:

If deaths occur within five days to a week, then by a week and a half investigations would surely start as people start dropping dead like flies. But probably about half of the people would be dead by the time they figure out what's going on and more dying by the moment while they race to quarantine people

Answer 3

Patient Zero (and all the initial victims) can also speed up the discovery of the disease if they have family members who are trained medical professionals. Such victims would naturally get superior medical care from their loved ones, including medicines to minimize the severity of the misdiagnosed "head cold". As soon as those medicines failed to work, additional lab work might be ordered, revealing the non-"head cold" nature of the pathogen.